Hall of Mirrors
by Linwe Elendil
Summary: Kate is needed in an alternate reality to face off against Ari. But can she defy fate? SG-1 crossover. Both AU. More details inside.
1. Prologue

Disclaimer: I do not own the rights to NCIS or SG-1. Not that that should come as a surprise to anyone…

Confusing as it may sound, this story is a crossover for Navy NCIS and Stargate SG-1 (that's not the confusing part). However, both shows are presented here in an alternate reality. So don't expect things to be exactly as you remember them.

I would explain more, but maybe it would be easier to just read the story…

* * *

Gibbs settled into his chair, just resting his coffee next to his monitor when a file slammed down on his desk, sending the cup flying. Staring at where his morning salvation had just been, he sighed. A stammered apology reached his ears – betraying the identity of the person responsible. McGee.

"This had better be important Agent McGee," he said without looking up, "or you will be starting your new career as a janitor in about two seconds."

"Uh, yes sir, it is sir." Gibbs looked up at the man, who actually managed to hold in his wince as he continued. "Sorry about your coffee, sir."

"If you know what's good for you McGee, you'll stop talking about my coffee and tell me what was so damn important."

The agent nodded. "Uh… yes. Sir." He opened the file, which Gibbs started to peruse. "A Colonel Jack O'Neill is on his way, sir. I've tried to look into his background, but most of it appears to be classified. He's requested a meeting with you and Agent Todd."

Kate looked up from her computer. "Me? Did he say why?"

"No, ma'am. Just that he wanted to see the two of you as soon as he arrives."

"Well, when is he arriving Agent McGee?" Gibbs asked.

The man checked his watch. "In about an hour, sir."

Gibbs waved a hand. "Alright – you and DiNozzo take a ride to the airport and pick him up."

"Yes, sir," was McGee's reply.

"Uh, boss… Don't you think that it would be better if I stayed here?"

"And do what, DiNozzo?" Gibbs turned his stare to the agent. "Got something you're working on that can't wait?"

Tony sucked a breath in through his teeth. He held it for a second before saying, "As much as I would like to lie and say yes…" he sighed, "I'm gonna have to go with a no."

"Then get outta here." Tony flinched.

"Right away, boss."

As the two men left, Gibbs stood and grabbed the file, walking over to Kate's desk. He sat down on the corner. "What do you make of him?" he asked, dropping Jack O'Neill's information in front of her. She read the file for a moment.

"Hmm… He's already retired once, so whatever brought him back to the military must've been important. Though it looks like there are a few gaps in his early service record, too." She continued reading. "Married twice. Divorced once, and the second wife died – doesn't say how. One son, victim of an apparent accident with his dad's gun. That fits with the recorded depression of the same year, and the divorce a year later." She closed the file and looked up. "Other than the obvious, there's not much I'll be able to tell you until I meet the man."

He gestured to her computer. "Why don't you look him up? You're still cleared for Air Force One, right?"

"Already tried that, when McGee said he wanted to meet me. I got nothing on him. It's almost like the man doesn't exist, Gibbs. I couldn't even find his fingerprints on file."

Gibbs rubbed his forehead. "I guess we'll find out soon enough." He stood and headed for the elevator. "I'm going to go get some more coffee. Call me if the Colonel shows up."

"You got it," Kate replied.

* * *

Normal so far, right? The differences will become apparent in the next chapter.

Thanks for reading!


	2. Explanations

Disclaimer: I bought SG-1 Season 1! But I still don't have NCIS… Or the rights to either show. Sigh…

Wow! I guess I should have been writing crossovers all this time! This one has generated interest more quickly than all but one of my other stories! I am happy to announce that the last chapter has been written, but now I'm working on all the stuff in between. ;-)

* * *

Kate tried a few more tactics while digging for information about Colonel Jack O'Neill. She tried aliases, spelling his last name differently, and doing a data search on all Colonels of his approximate age. Still nothing. All she could resort to was staring at the service record of a decorated soldier who just didn't seem to exist. She couldn't understand why, but something about the man made her shiver. It wasn't that she was afraid of him, though the unknown was never as satisfying as an ordered picture of the world. It was something else. She groped for the right word as she stared at the man's silver hair.

_Destiny._

"He's here, Kate." Gibbs voice snapped her roughly from her thoughts, and she gasped in surprise. Had it really been an hour? She swallowed, doing her best to push down the lingering butterflies in her stomach. Closing the file, she stood.

"Then let's go meet our mystery guest," she said, with more confidence than she truly felt.

Gibbs looked into her eyes. He knew she was afraid, but apparently chose not to mention it. He nodded slowly. "By all means, Agent Todd." He gestured with one arm, letting her lead the way. Kate blinked. She was used to having to run to catch up with the man. But here, she was given prerogative. Nodding back, Kate started toward the meeting room. Though she tried very hard to see things from a different point of view, she felt out of control and slightly helpless.

Like someone on their way to the firing squad.

xXx

Colonel O'Neill turned out to be a charming man in his early 50's. Sitting across the table, Kate found it hard to believe that she had been frightened of him. Concealing a sigh of relief, she brought her mind back to the business at hand. Gibbs had taken charge of the meeting – which felt more like an interrogation.

"So… Colonel O'Neill. One question. Who exactly are you?"

The Colonel's eyebrows rose. "I fly all the way here from Washington State, and that's the only question you have?"

"Oh, that one's just for starters." Gibbs opened the man's service record and slid it across the table. "This paints a rather interesting picture of you, Colonel. But other than the fact that the Air Force seems to have paid for your plane ticket, I can't find anything that indicates you're currently serving in the military." He slid the folder across the desk. The Colonel reached out a hand to grab it before it slipped to the floor as Gibbs said, "Frankly, _sir_ –" there was a hint of sarcasm here, "I just don't see a good reason why I should trust you around my team." He sat back, his eyes daring the man to explain everything.

Colonel O'Neill chuckled and waved a finger at Gibbs. "I knew you were holding out on me. 'One question' my ass…"

"Why aren't you answering it?" Kate asked, folding her arms across her chest. Out of the corner of her eye, she saw Gibbs give her a small smile. It increased her confidence. "Let's cut the preliminaries, Colonel. Who are you, and what are you doing here?" She wanted to add _"What do you want with me?"_ but decided to stick with the basics. For now.

"Do you two always talk so much?" the Colonel shot back. He raised a hand before either of them could complain again. "My name _is_ Colonel Jack O'Neill, and I _am_ currently serving with the Air Force." He looked at Gibbs. "I trust you've heard the phrases 'Covert Operations' and 'Top Secret' before?"

Gibbs tilted his head slightly. "To be _this_ covert and secret, you'd have to be working at Area 51, Colonel."

The man took a deep breath before blowing the air forcibly from his lungs. "Call me Jack, okay?" He leaned back in his chair, looking for all the world like a veterinarian who had to tell a six year old that their beloved dog was dead. "As for aliens, or 'little green men'…" he sighed again, shaking his head, "You have no idea."

xXx

Two hours of explanation later, Jack was beginning to get a headache. The woman was asking so many questions, that he had to push back memories of Sam, his late (and very lamented) second wife. She had been just as persistent. Kate continued her barrage. "So you use this 'Stargate' to travel across the known universe, arriving at similar gates, where you find other sentient species?"

Jack pinched the bridge of his nose. "Believe me, Special Agent Todd, we travel outside the known universe on a regular basis." The woman shook her head, and Jack knew he was in for another question. He needed a cup of coffee.

"Why should we?" She sat back. "Believe you, that is."

"Look," Jack said, placing his hands on the table as he searched for a sense of calm. "Get me some caffeine and a computer, and I'll show you everything." The two NCIS Agents looked at each other. The woman just blinked, and Gibbs nodded.

"We'll be right back," he said, standing. She did the same. They both headed for the exit, and Jack knew he would be fair game the second the door closed. _Let them talk,_ he thought as he loosened his tie and unbuttoned his collar. _Heaven knows I had a hard time accepting the truth – even when it was right in front of me._

xXx

Gibbs didn't even wait for the door to close. They started down the hall as he said, "Well?"

Kate shrugged. "He certainly believes everything he's told us – though I have to leave room for the possibility that he's delusional."

He shook his head. "If he's lost it, I doubt the Air Force would need to send him to us, Kate. They could've figured that out by themselves." He started down the stairs to the bull pen. "I think what we have to leave room for is the possibility that he's telling the truth."

"Frightening possibility," Kate admitted as she followed Gibbs to his desk.

"Uh, huh," he said in agreement as he leaned over to check something on his monitor. He looked back up at her. "You get a laptop, I'll get the coffee."

"None for me, thanks," Kate said as she turned on her heel.

"One thing I am sure of," Gibbs said, making her turn back for a second. He put a finger to his lips and Kate smiled as she thought of her fascinated-by-all-things-paranormal friend.

"Don't tell Abby."

"You got it," Gibbs replied as he stood to get the coffee.

* * *

Well, I think I got things going at a pretty good clip now! I would write more, but it's late, and I need to get some sleep! I'm moving tomorrow, after all!

But I think this is going well so far, don't you?

…

Right?

:-S


	3. Doppelganger

Disclaimer: Still no rights. Still not sure what my muse is doing, but at least I know the end on this one!

More differences become apparent here. I hope it's not too confusing!

* * *

Jack stared at the coffee Gibbs had just placed in front of him. He doubted even Daniel would have touched the stuff. "I'm beginning to wonder if the Air Force and the Navy buy the same coffee," he said, wincing as he took a drink.

Gibbs smiled. "I guess they figure that whatever doesn't kill you…"

"Makes you stronger," Jack finished. "Yeah, I thought it might be something like that." He took another drink. "I'll give 'em one thing – it does seem to grow on you."

"If you like facial hair," Kate interjected. She had just walked in, holding a laptop and another file. She set the computer in front of Jack and handed the file to Gibbs. "Everything I could find on the Stargate program. Though I don't think it's going to be of much help. According to the file, it's an astrology project whose applications are limited."

"Cover-up" Jack said. "What did you expect to find, Special Agent Todd?"

"Kate," she replied and shrugged. "Being former Secret Service, I thought I might find something that would corroborate your story."

"It was a nice try, Kate. But that's why I wanted the computer. I figured you would get stonewalled." Jack opened the laptop. "Now… where's the power button again?"

Gibbs laughed as Kate went over to help. Within a minute, Jack had found the secured site and entered his login and password. He brought up the details of the Stargate project and slid the computer across the table, waiting in silence as Kate and Gibbs read its contents.

"Okay…" Gibbs was the first to respond. "So why does the Air Force need our help? Sounds like you guys are doing pretty good against these…" he glanced back at the screen, "Guld?"

"Goa'uld" Jack corrected. "And you're right. That's not why we need you."

"Why then?" Gibbs countered.

Jack took a deep breath. "And here comes the tough part." Grabbing the computer again, he typed in a few more commands before sliding it back to the NCIS agents. They took a few minutes to read the new information that it showed. This time it was Kate who responded.

"So this mirror lets you travel through different times?"

"More like different timelines."

"Are you trying to say…?"

He nodded. "I'm not from your reality." Gibbs' eyes narrowed. Kate just stared.

"And you expect us to believe this?" she asked, incredulous.

Jack looked at her. "Not only do I need you to believe it, I need _you_ to come back there with me."

"To your 'reality'."

"Yes."

"Why?" Gibbs asked.

Jack sighed. "How much do the two of you know about Ari Haswari?"

Kate's brow furrowed. "He was a terrorist. Smuggled himself into NCIS Headquarters and took our ME, his assistant, and myself hostage." Jack nodded.

"In my timeline he's the leader of a group calling themselves the Truth Faction. He's trying to get his hands on Goa'uld technology. We don't know what he plans on doing with it. Our hypotheses range from using it to conquer to country, to simply showing it off to the world. And he doesn't care how he gets it – he doesn't shy away from murder."

"Best guess…?" Kate trailed off.

"Simply put – the man wants power. No matter what it costs the world in our fight against the Goa'uld. Hell, if he had a chance, he would probably join them. Though I think he would turn tail and run if he saw what they do to their hosts."

"What do they do?" Kate asked.

"Trust me, you don't wanna know," was all Jack said in reply.

"So what do you need me for?" she asked.

"I need you to kill Ari Haswari before he gets his hands on the technology. We believe that once he's dead, the faction will lose steam."

"Cut off the head and the body will die," Gibbs interjected.

"That's what we're hoping," Jack answered.

Kate shook her head. "I don't understand. Why can't Gibbs go?"

"To be frank, he's not Ari's type."

Gibbs sat up. "Are you saying that you want Kate to –"

"No!" Jack said. "But we need someone who can get close to Ari. Someone he trusts. The Kate in my timeline is the only one who has that kind of access. She's his… girlfriend, of sorts."

"Of sorts?" Kate shot at him.

He ignored her. "We captured 'Kate' four days ago. Ever since Ari found out, he's been threatening to slaughter innocent civilians if we don't return her. Deadline is two days away. We can't let that happen, but we can't afford to release Kate, either. Without her, he's not as much of a threat. So we decided to use the mirror – something we think he doesn't know about yet – to search for a replacement. Someone who can get close to him."

"And kill him," Kate said, grimly.

"Yes," Jack replied without flinching. "Once you see what Ari has done, believe me, you won't mind putting a bullet in his head."

"Why her?" Gibbs asked. "Can't you use this mirror to find another Kate? Someone else who can assassinate Ari?" Kate felt a rush of gratitude toward her boss. He didn't want her to do this anymore than she wanted to herself.

"We've tried that." Jack sighed. "There's something else you two need to know." He looked directly at Kate, and his eyes were sad. "It's not going to be easy for you to hear, but in all the alternate realities I visited, this is the first one where I found you alive."

"What?" she asked, confused. "Do you mean to say that I'm dead in every other reality?"

"I can't confirm that the same thing happened in every reality – only the ones I visited. But there's something else… the way you died…" Kate swallowed hard. She knew what was coming. "You were murdered by Ari."

"In every single one?" Gibbs shot at him. "How is that possible?"

"I don't know," Jack replied, "But that's what I found." He turned back to Kate. "It took me three days to find you. I don't have time to start over."

Kate was reeling. It was one thing to hear that there were aliens out there, and another to hear that alternate realities existed. But to learn that you had been murdered in _all_ other timelines? She couldn't process the information.

"How come I'm still alive here, then? Why didn't Ari kill me?"

Jack ran a hand through his hair. "Near as I could discover, it has something to do with Gibbs. In your first meeting with Ari, he gave you the chance to shoot him, didn't he?"

"Yes," Gibbs replied, "Though it was the _only_ meeting I had with that bastard."

"That's right," Jack said. "I forgot. What happened?"

"I shot him in the head," Gibbs replied dispassionately.

"You killed him, then."

"Yes."

"In the other realities I saw, you didn't go for a head shot. Double-tap to the chest. But he was wearing a bullet-proof vest. Because he survived that encounter, he later killed Kate. It varies as to when, but it's usually the same way. Single bullet to the brain. It seems to be his favorite MO in just about every timeline." He ground his teeth together, and Kate guessed that he was hiding something, but she wouldn't push it yet. She would know soon enough.

Gibbs shook his head. "So, it's because _I_ shot _him_ in the head, that Kate's still alive?"

"That about covers it," Jack replied.

Kate sat back in shock. She closed her eyes and took a deep breath, letting it out slowly. Was she living on borrowed time? She had never been one to believe in destiny before, but something about this situation was making her second guess herself. Everything she had heard in the last hour tumbled around her brain. She couldn't get the information to settle, and trying to force it to do so only gave her a headache.

It sounded like her doppelganger had chosen a life far different from her own. Could she step into that woman's shoes? In the dark corner of her mind, a memory surfaced. Standing face to face with Ari – the scalpel in her hand. One slice was all it would have taken. One single moment, suspended in time. But she had hesitated. That hesitation, and a slight difference in aim from Gibbs had meant her eventual death in every other variation of the events. Her life hung by such a fragile thread. Who was she to decide where her fate rested now? As much as she wanted to call security and have the Colonel escorted from the building, she found herself nodding. Her eyes opened wide in surprise as she looked at the two men sitting at the table. Placing her hands in her lap – hoping Gibbs wouldn't notice them shaking – she cleared her throat.

"I'll do it," she said.

* * *

Hope you enjoyed!

Review? Please?


	4. Reasoning

Disclaimer: Same as usual. I don't have the brain power to think of something clever right now. Sorry.

Okay, so I've changed my mind! Or rather, my muse has changed it for me! I do not think there will be a character death after all! I even went so far as to take that disclaimer off the description of the story. I'm much happier with the way things will turn out. I think…

* * *

Kate buried her head in the file, doing her best to appear calm. As soon as she had given her answer, Colonel O'Neill had flown into action. He pulled out a dossier on her alter ego, and spent an hour on the phone with his boss in Cheyenne Mountain. Kate tried to read, but found herself too nauseas to concentrate. It didn't help that Gibbs was staring her down, either. She hoped his attention would soon be diverted somewhere else, or she might just change her mind.

When O'Neill hung up, Gibbs turned to talk to him. Their voices weren't soft – if she'd been paying attention, she would have heard their conversation. Instead, she stared at the photo of the scowling woman before her – wondering what set of circumstances could have led her into such a different life than her own. Not that she had any right to dictate someone else's future. Or was it her past? She was getting a headache again.

"Kate," Gibbs said, snapping her out of her reverie, "Let's go." She nodded and stood, not bothering to ask where. At this point, did it really matter? In a few hours she'd be on a plane to a secret military installation, and then off to another world. Who cared about the next few minutes? It turned out that Gibbs did. The second the elevator doors closed before them, Gibbs hit the emergency stop. He stared forward. Neither of them spoke.

Gibbs finally broke the silence. "Welcome to my office, Agent Todd," he said. She tried to smile, but couldn't. He turned to look at her, and she couldn't resist the pull of his eyes. They seemed to see into her soul, and Kate absently wondered what he found there. "One question," he said, never looking away. She didn't dare blink. "What the _hell_ are you thinking, Kate?"

"What?" Whatever she had been expecting, that wasn't it.

"Why? Why are you going halfway across the country – no, scratch that – why are you leaving your _entire_ life behind? To save humanity as _**they**_ know it? C'mon…"

Kate tried not to stutter. "This is something I think I have to do."

"Don't give me that crap."

Her brain jumped to defensive mode. "You heard the Colonel, sir. He doesn't have time to find anyone else."

"Well why can't he make a deal with this other 'Kate'? Get her to kill that bastard Ari?!"

"Would you make a deal with her?" He sighed, and she knew she had him. He never made deals with anyone. "I have to do this, and I think you know that." Determination crept into her voice, with a fierceness that surprised her.

"Yeah, I know. I just wanted to make sure that you do."

Kate smiled for the first time since coming to work that morning. Talk about a backward pep talk – strengthening her resolve to go while telling her to stay. Only her boss could have pulled that one off. "Thanks, Gibbs." He nodded and cancelled the emergency stop. They traveled the short distance to Abby's lab in silence. Only as the door opened did Gibbs speak again.

"Be careful," he whispered.

* * *

Short, I know. But the next one should be coming soon! I have finished the last two chapters, and there's only one more between that one and this…

:-)


	5. Door Number One

Disclaimer: We all know the story by now. Don't own nothin'. Oh, well.

* * *

Kate walked into Abby's lab, fighting to keep her face impassive. Loud music assaulted her ears, and the briefest smile lit her features. Abby never had been one for protocol.

"Lucky for her, she's damn good at her job," Gibbs practically yelled in Kate's ear.

The volume suddenly decreased as Abby turned to face them, a remote in her hand.

"Thanks, Gibbs." She smiled. "But you know you'd never get rid of me."

"Why's that?" he countered.

"You'd miss me too much."

Gibbs brought one finger to his lips before bouncing a fist against his chest. _I doubt it_, he'd just signed. Abby brushed her fingers across her chin and brought both hands down. _Liar_, she countered.

Without another word, Gibbs handed over the folder on the pseudo-Kate. It had been paired down to pictures only – wounds that the woman had sustained in her reality. Scars that Kate needed if the masquerade was to succeed. Abby flipped through them as Gibbs turned toward the exit.

"I'll be back in 30, Abbs. She'd better be ready."

"Aye, aye, Sir!" The dark haired woman tossed off a salute at her boss' retreating back before turning to Kate. "I recommend we get started with this one," she said, pointing to a particularly nasty scar in a rather embarrassing place, "Just in case Gibbs gets back early."

Kate threw up her hands. "No argument from me," she said, trying her best to laugh. It didn't come out right, and Abby looked at her sideways from the drawer she was already leaning into. She raised her eyebrows, silently questioning her friend.

"Undercover assignment," Kate replied. "Don't ask." Abby turned back to her supplies, grabbing at least a dozen assorted tubes, bottles, and containers before turning back to the folder.

"Hmm… I can do most of these, but we'll have to get Ducky up here for this one," she said, pointing to a jagged scar just under the woman's collarbone. "I'm not sure I have what I need to make this look realistic."

"Whatever it takes, Abby," Kate said, as she shucked her suit coat.

_Whatever it takes._

**xXx**

Thirty minutes later, Abby was just applying a last coat of glue to the final injury.

"There," she said, as the door opened. Gibbs strode over to the two women. Kate sat on the counter having long ago traded her business attire for fatigues and a tank top. He looked down her neck and arms – his eyes tracing the myriad of scars that now resided there.

"Good work, Abbs," he said, nodding in approval. Then his eyes found Kate's. Abby could read the hesitation in them; the concern. "Kate… Time to go."

She nodded and jumped off the counter, reaching for her camouflage jacket. Gibbs watched her the whole time, and Abby stared between the two of them. As Kate freed her ponytail from the jacket, Abby looked over at her boss.

"Gibbs… What's wrong?" He ignored her, his face tightly controlled. "Gibbs?" Kate stared at the floor, as if composing herself. Looking up at Abby briefly, she gave her friend a quick hug before walking swiftly from the room; her face staring resolutely forward – unwilling, or unable, to look back. Their boss followed after.

"Gibbs?" Abby said, louder.

He turned briefly. "Need to know, Abby." He got in the elevator with Kate, and as Abby watched the doors close, she couldn't help the feeling that something was wrong. Chills made their way up her arms, and one tear left a trail of black mascara down her cheek as she put a name to her fear.

Something told her she'd just sent her friend to her death.

* * *

(I know this one was short, but there are only two more chapters and an epilogue. And it's almost all written!)

Soooo… Review? Please?

Yes, there is sign language in here. That would be because I'm an interpreter, and I love the fact that Gibbs and Abby sign! I didn't want to go into too much detail for the signs, so if you'd like to know what they really look like, there are a myriad of websites you can try.


End file.
